Parametric temperature regulation of induction heated load

Abstract

A fuel delivery system for a vehicle includes a fuel injector that dispenses heated fuel flow and controls the temperature of the heated fuel within a desired temperature range. Fuel flowing through the example fuel injector is inductively heated by a valve element sealed with the fuel flow. A driver controller detects changes in temperature by monitoring changes in parameters that vary responsive to temperature in the material of the heated element. Changes in the material responsive to temperature are utilized to tailor input into the heated element to maintain a desired temperature of the heated element and thereby the temperature of the fuel.

What is claimed is: 
     
       1. A heated fuel injector driver circuit assembly comprising:
 an inductor, configured to provide a time varying magnetic field to a heating element, wherein the heating element is within a fuel flow and separate from the inductor; 
 a monitor that senses energy supplied to the inductor and provides a first output voltage value, the energy supplied to the inductor being provided by an oscillator coupled to said inductor; 
 a converter that converts a frequency that changes responsive to changes in temperature of the heating element into a second output voltage value; 
 a computational engine that combines the first output voltage value and the second output voltage value to obtain a scaled voltage value; 
 an error amplifier that combines the scaled voltage value with a target value to obtain an error value; 
 a comparator that compares the error value to a periodic waveform to adjust power provided to the inductor to maintain a desired temperature of the heating element; 
 wherein the monitor comprises a current-sense resistor that monitors current supplied to the inductor and wherein the oscillator comprises a synthetic power inductor, configured to change an output frequency of the oscillator and thereby control the energy that is provided to the inductor; and 
 wherein the heating element is a fuel injector valve, the fuel injector valve being coupled to an armature, the armature being coupled to a driver coil. 
 
     
     
       2. The heated fuel injector driver circuit assembly as recited in  claim 1 , wherein the converter converts a phase of the current at the inductor into a voltage that is indicative of the phase. 
     
     
       3. The heated fuel injector driver circuit assembly as recited in  claim 1 , wherein error amplifier combines a current monitored from the current-sense resistor with the voltage value indicative of frequency to obtain a frequency corrected current value. 
     
     
       4. The heated fuel injector driver circuit assembly as recited in  claim 3 , wherein the frequency-corrected current is differentially amplified relative to a target current value. 
     
     
       5. The heated fuel injector driver circuit assembly as recited in  claim 4 , wherein a higher frequency-corrected current is indicative of an increase in temperature that triggers a reduction in power provided to the inductor. 
     
     
       6. The heated fuel injector driver circuit assembly as recited in  claim 4 , wherein a lower frequency-corrected current is indicative of a decrease in temperature that triggers an increase in power provided to the inductor.